Conclusions

In section 1 the statement has been made that short roundtrip times are more important than high throughput values, because short roundtrip times are essential for fast message passing between remote cluster running a distributed application, while the size of these messages is in general small.

Keeping this in mind, it is clear from the presented results in section 4 that at the beginning of the monitoring period the roundtrip times across the Internet are too large for remote distributed applications. During the monitor period the roundtrip times improved a lot. At the end of the period the difference between ATM and Internet roundtrip times become much less. In some cases the roundtrip times across the Internet routes are shorter than across the corresponding ATM route, but these differences are topology dependent.

Please note that the used Internet routes are in general not very optimal. The interconnection of the DAS clusters was of course focussed to the ATM network: the ``normal'' Internet route was generally not used, so a short Internet connection from the gateways to the backbone had no priority. Therefore, the Internet roundtrip results may be somewhat pessimistic.

It is difficult to conclude that the current roundtrip times are sufficient for remote applications, because each application has its own characteristic properties. Some benchmarking is needed to bring clarity at this point. However, considering the future investments of SURFnet into the research network, one may expect that a more direct connection of the DAS clusters at the backbone should improve the current situation still more. On the other hand the capacity of the clusters with DAS 2 will also increase. This may lead to the situation that Quality-of-Service aspects are also needed in the future which may also have interesting aspects from a research viewpoint.

Also the recent Internet throughput values show a considerable improvement compared with the older ones. There are still more variations than at the values from the ATM routes, but the Internet throughput values are seldom lower than 3 Mbit/s: often they are larger than the values obtained from the ATM routes, from which the recent values are somewhat lower than the older ones. So we do not expect that the bandwidths of the Internet routes form limitations for remotely distributed applications.